Re: [PATCH] tpm: Wrap the buffer from the caller to tpm_buf in tpm_send()

[Jerry Snitselaar]

On Mon Sep 16 19, Jarkko Sakkinen wrote:
> tpm_send() does not give anymore the result back to the caller. This
> would require another memcpy(), which kind of tells that the whole
> approach is somewhat broken. Instead, as Mimi suggested, this commit
> just wraps the data to the tpm_buf, and thus the result will not go to
> the garbage.
>
> Obviously this assumes from the caller that it passes large enough
> buffer, which makes the whole API somewhat broken because it could be
> different size than @buflen but since trusted keys is the only module
> using this API right now I think that this fix is sufficient for the
> moment.
>
> In the near future the plan is to replace the parameters with a tpm_buf
> created by the caller.
>
> Reported-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> Suggested-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 412eb585587a ("use tpm_buf in tpm_transmit_cmd() as the IO parameter")
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> ---
> drivers/char/tpm/tpm-interface.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index d9ace5480665..2459d36dd8cc 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -358,13 +358,9 @@ int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
> 	if (!chip)
> 		return -ENODEV;
>
> -	rc = tpm_buf_init(&buf, 0, 0);
> -	if (rc)
> -		goto out;
> -
> -	memcpy(buf.data, cmd, buflen);
> +	buf.data = cmd;
> 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command");
> -	tpm_buf_destroy(&buf);
> +
> out:
> 	tpm_put_ops(chip);
> 	return rc;
> --
> 2.20.1

Nothing uses the out label any longer so it should be dropped as well, but other than that...

Acked-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>